It is common to provide electric motors with suppression elements to prevent or reduce electrical interference which, in automotive environments, may impair the functioning of on-board microprocessors. Typically, these elements take the form of a choke connected in series between a power supply terminal and a motor brush or a capacitor connected between a motor brush and earth or between two motor brushes. Diodes may also be used in more sophisticated suppression circuits. These suppression elements are conveniently mounted on the motor end cap. However, for smaller size electric motors, it is often difficult to accomodate these suppression elements in the end cap. One way to overcome this difficulty is to provide a two-part end cap and to accommodate the suppression elements between the two parts of the end cap.
Thus, as disclosed in UK Patent Specification No. 2 222 316, it is known to provide an end cap assembly, for a fractional horsepower PMDC electric motor, comprising an inner part having internal and external surfaces; brush gear mounted on the internal surface of the inner part; a suppression element mounted on the external surface of the inner part in electrical contact with the brush gear; an outer part shaped for axial engagement with the inner part and formed with at least one terminal aperture; and a terminal extending through the aperture.
In this case, the terminal is mounted in the inner part and the outer part serves as a protective cover for the suppression element. Separate means must therefore be provided for supporting the suppression element on the external surface of the inner part, for making a permanent connection between the suppression element and the brush gear and for making a permanent connection between the terminal and the suppression element.
This results in a complicated structure which, as a consequence, is relatively difficult and costly to produce.
The purpose of the present invention is to overcome or at least reduce these disadvantages and to provide a two-part end cap assembly of simpler construction which is easier and less costly to produce.